On Independence Square in Kiev this morning, a 62-year-old Ukrainian, Igor Voscovonyanko(ph), was venting his frustration. Russia is effectively occupying part of his country, Crimea, and he's not convinced economic sanctions or anything else can stop Russia's president Vladimir Putin.

IGOR VOSCOVONYANKO: It is not enough. They are not enough because Putin's will is only occupation.

MONTAGNE: President Obama has imposed sanctions on Russians involved in the aggression in Ukraine. But the reality is, for now, he seems to have little leverage over Putin.

In a moment, we'll talk about the broader diplomatic consequences of a breakdown in the Obama-Putin relationship.

GREENE: But first, there's someone familiar with both men. Author Angela Stent, she's advised to administrations on Russia and attended policy dinners with President Putin. I asked her what they think of one another.

ANGELA STENT: We've heard from President Obama that the best thing he said about Mr. Putin is that he's pragmatic and you can do deals with and that the U.S. and Russia can work together. But we've also heard President Obama make remarks like Putin looks like the bored kid slouched at the back of the classroom. President Putin, I've heard him say fairly positive things about President Obama, i.e., we could work together. But I've also heard him talk about President Bush in what sounded at least to me it like warmer way. He spoke about my friend George and how they worked together.

Now, subsequently, that attitude towards President Bush changed. But I've never heard certainly, President Putin use the word friend to describe President Obama.

GREENE: Let me follow up on the Russian-Georgian war. In 2008, ties were frayed very badly between the United States and Russia. Obama comes in, talks about a reset. Was the reset ever realistic?

STENT: I think it was realistic because in the beginning, President Obama was dealing with the new president, Dmitry Medvedev. And by all accounts, those two presidents got on rather well - even though the U.S. quite understood that Mr. Putin was still the chief decider. And, you know, it accomplished quite a bit, if you think about the New START Arms Control Treaty, cooperation on tougher sanctions on Iran, cooperation on opening a new way to transport troops and material to and from Afghanistan, where we cooperated with Russia. Because it was very much based on areas where we had common interests and the U.S. was less focused on what was happening inside Russia.

GREENE: Well, if there are general interests that Vladimir Putin is pursuing, why would you have the German chancellor quoted as saying that he seems not to be operating in reality?

STENT: Well, even in these gatherings that we've had with him over the past 10 years, there are some times when he makes statements and gives an assessment to facts that are just completely at odds with what other people's understanding is. So I think that it's true that his understanding of the world is probably quite at odds with that of either, Chancellor Merkel, President Obama or anyone else. I think that's maybe because as he has become more powerful - and I would argue may be more isolated from what's going on on the ground - he probably listens to the advice and information from a rather small group of people, and they probably reinforce his belief - which he apparently has - that Ukraine is, you know, about to be taken over by, quote - unquote, "Fascists supported by the West."

GREENE: You think he generally believes things like that - this is not something he's saying, you know, for political reasons?

(LAUGHTER)

STENT: You know, I'm not a psychiatrist. All I can say is it's possible that he believes some of that. I think he certainly believes that the U.S. is interested in regime change, not only in places like Iraq, but in right up to Russia's borders and possibly in Russia itself. And I think that probably informs the way he views what is happening in Ukraine.

GREENE: We began this conversation with you saying that Barack Obama says that Vladimir Putin is someone he can make deals with. Is there anything that he can do to work out some sort of diplomatic resolution with Putin?

STENT: Well, I think the reality is the U.S. has quite limited leverage her in the short run. In the longer run, you know, if there were hard-hitting extensive sanctions against Russia that could have an impact - but then, of course, that would also impact American and European businesses too. So the reality of life is that Russia is right next door. It has its troops there. Reclaiming Crimea is much more important for Russia than not having Crimea joining Russia is for either the U.S. or the Europeans, so we have very limited leverage there.

GREENE: That is Angela Stent. Her new book is called, "The Limits of Partnership: U.S.-Russian Relations in the Twenty-First Century." Transcript provided by NPR, Copyright NPR.